Loss of keratin 13 in oral carcinoma in situ: a comparative study of protein and gene expression levels using paraffin sections

Unraveling the Keratin Expression in Oral Leukoplakia: A Scoping Review

Intermediate filaments are one of three polymeric structures that form the cytoskeleton of epithelial cells. In the epithelium, these filaments are made up of a variety of keratin proteins. Intermediate filaments complete a wide range of functions in keratinocytes, including maintaining cell structure, cell growth, cell proliferation, cell migration, and more. Given that these functions are intimately associated with the carcinogenic process, and that hyperkeratinization is a quintessential feature of oral leukoplakias, the utility of keratins in oral leukoplakia is yet to be fully explored. This scoping review aims to outline the current knowledge founded on original studies on human tissues regarding the expression and utility of keratins as diagnostic, prognostic, and predictive biomarkers in oral leukoplakias. After using a search strategy developed for several scientific databases, namely, PubMed, Scopus, Web of Science, and OVID, 42 papers met the inclusion and exclusion criteria. One more article was added when it was identified through manually searching the list of references. The included papers were published between 1989 and 2024. Keratins 1-20 were investigated in the 43 included studies, and their expression was assessed in oral leukoplakia and dysplasia cases. Only five studies investigated the prognostic role of keratins in relation to malignant transformation. No studies evaluated keratins as a diagnostic adjunct or predictive tool. Evidence supports the idea that dysplasia disrupts the terminal differentiation pathway of primary keratins. Gain of keratin 17 expression and loss of keratin 13 were significantly observed in differentiated epithelial dysplasia. Also, the keratin 19 extension into suprabasal cells has been associated with the evolving features of dysplasia. The loss of keratin1/keratin 10 has been significantly associated with high-grade dysplasia. The prognostic value of cytokeratins has shown conflicting results, and further studies are required to ascertain their role in predicting the malignant transformation of oral leukoplakia.

The increased expression of cytokeratin 13 leads to an increase in radiosensitivity of nasopharyngeal carcinoma HNE-3 cells by upregulating ERRFI1

The main factors contributing to the unfavorable outcome in the clinical treatment of patients with nasopharyngeal carcinoma (NPC) patients are radiation resistance and recurrence. This study aimed to investigate the sensitivity and molecular foundation of cytokeratin 13 (CK13) in the radiotherapy of NPC. To achieve this, a human NPC cell line overexpressing CK13, HNE-3-CK13, was constructed. The effects of CK13 overexpression on cell viability and apoptosis under radiotherapy conditions were evaluated using the CCK-8 assay, immunofluorescence, and western blotting (WB). Next-generation sequencing was performed to identify the downstream genes and signaling pathways of CK13 that mediate radiotherapy response. The potential role of the candidate gene ERRFI1 in CK13-induced enhancement of radiosensitivity was investigated through rescue experiments using clone formation and WB. The effects of ERRFI1 on cell viability, cell apoptosis, cell cycle, and the related key genes were further evaluated using CCK-8, immunofluorescence, flow cytometry, quantitative polymerase chain reaction and WB. The results showed that CK13 overexpression in HNE-3 significantly inhibited cell survival under radiotherapy and promoted apoptosis marker γH2AX expression, leading to a significant increase of ERRFI1. Knockdown of ERRFI1 rescued the decreased cell viability and proliferation and the increased cell apoptosis that were caused by CK13 overexpression-mediated radiotherapy sensitization of NPC cells. In this process, EGFR, AKT, and GSK-3β were found involved. In the end, ERRFI1 was proven to inhibit expression levels of CDK1, CDK2, cyclin B1, and cyclin D1, resulting an increased G2/M cell ratio. Overexpression of CK13 enhances the radiosensitivity of NPC cells, which is characterized by decreased cell viability and proliferation and increased apoptosis. This regulation may affect the survival of HNE-3 cells by increasing the expression of ERRFI1 and activating the EGFR/Akt/GSK-3β signaling pathway, providing new potential therapeutic targets for the treatment of NPC.

Targeting the KRT16-vimentin axis for metastasis in lung cancer

Lung cancer is the most diagnosed malignant cancer and the leading cause of cancer-related deaths worldwide, with advanced stage and metastasis being a major issue. The mechanism leading to metastasis is not yet understood. Here, we found that KRT16 is upregulated in metastatic lung cancer tissues and correlated with poor overall survival. Knockdown of KRT16 inhibits metastasis of lung cancer both in vitro and in vivo. Mechanistically, KRT16 interacts with vimentin, and depletion of KRT16 leads to downregulation of vimentin. KRT16 acquired its oncogenic ability by stabilizing vimentin, and vimentin is required for KRT16-driven metastasis. FBXO21 mediates the polyubiquitination and degradation of KRT16, and vimentin inhibits KRT16 ubiquitination and degradation by impairing its interaction with FBXO21. Significantly, IL-15 inhibits metastasis of lung cancer in a mouse model through upregulation of FBXO21, and the level of IL-15 in circulating serum was significantly higher in nonmetastatic lung cancer patients than in metastatic patients. Our findings indicate that targeting the FBXO21/KRT16/vimentin axis may benefit lung cancer patients with metastasis.

Cytokeratin 13 promotes radiotherapy sensitivity of nasopharyngeal carcinoma by downregulating the MEK/ERK pathway

BACKGROUND

Radiation therapy is the first treatment choice for nasopharyngeal carcinoma (NPC), while radiation resistance and recurrence have become the primary factors and are associated with poor prognosis in the clinical treatment of NPC patients. The purpose of the present study was to explore the sensitivity and molecular basis of cytokeratin 13 (CK13) that regulates NPC radiotherapy.

METHODS

HNE-3 or C666-1 cell line was used for overexpression and knockdown tests. Under radiotherapy conditions, CCK-8 assay, clone formation assay, and flow cytometry analyzed the effects of CK13 overexpression on cell proliferation, apoptosis, and cell cycle, respectively. In addition, Western blotting detected CK13-mediated downregulation of cell cycle-related genes. The mouse subcutaneous tumor-bearing experiment identified the effects of CK13 overexpression on the treatment of NPC in vivo. Further, Western blotting, CCK-8 assay, and flow cytometry investigated whether the CK13-mediated cell apoptosis involves the MEK/ERK signaling pathway.

RESULTS

Overexpression of CK13 significantly inhibited the survival of HNE-3 cells under radiotherapy in vitro and in vivo, and there was a substantial decrease in cyclin-dependent kinase 4 and 6 (CDK4/6) levels promoting the cell percentage number in the G2/M phase and, subsequently, the ratio of the apoptotic cells. In contrast, the knockdown of CK13 showed the opposite partial regulatory effect. Interestingly, CK13 overexpression also showed a reduction in the survival of C666-1 cells and an increased ratio of the apoptotic cells under radiotherapy treatment. Furthermore, higher levels of CK13 downregulated the MEK/ERK signaling pathway, resulting in decreased HNE-3 cell proliferation and increased apoptosis. However, ERK activators were able to rescue the process partially.

CONCLUSIONS

Together, these results showed that CK13 promoted the radiosensitivity of NPC cells by downregulating the MEK/ERK signaling pathway. Thus, targeting CK13 provided insights into the treatment of NPC radiotherapy.

Utility of Keratins as Biomarkers for Human Oral Precancer and Cancer

Human oral cancer is the single largest group of malignancies in the Indian subcontinent and the sixth largest group of malignancies worldwide. Squamous cell carcinomas (SCC) are the most common epithelial malignancy of the oral cavity, constituting over 90% of oral cancers. About 90% of OSCCs arise from pre-existing, potentially malignant lesions. According to WHO, OSCC has a 5-year survival rate of 45–60%. Late diagnosis, recurrence, and regional or lymph nodal metastases could be the main causes of the high mortality rates. Biomarkers may help categorize and predict premalignant lesions as high risk of developing malignancy, local recurrence, and lymph nodal metastasis. However, at present, there is a dearth of such markers, and this is an area of ongoing research. Keratins (K) or cytokeratins are a group of intermediate filament proteins that show paired and differentiation dependent expression. Our laboratory and others have shown consistent alterations in the expression patterns of keratins in both oral precancerous lesions and tumors. The correlation of these changes with clinicopathological parameters has also been demonstrated. Furthermore, the functional significance of aberrant keratins 8/18 expression in the malignant transformation and progression of oral tumors has also been documented. This article reviews the literature that emphasizes the value of keratins as biomarkers for the prognostication of human oral precancers and cancers.

Identification of Urine Biomarkers to Improve Eligibility for Prostate Biopsy and Detect High-Grade Prostate Cancer

PCa screening is based on the measurements of the serum prostate specific antigen (PSA) to select men with higher risks for tumors and, thus, eligible for prostate biopsy. However, PSA testing has a low specificity, leading to unnecessary biopsies in 50-75% of cases. Therefore, more specific screening opportunities are needed to reduce the number of biopsies performed on healthy men and patients with indolent tumors. Urine samples from 45 patients with elevated PSA were collected prior to prostate biopsy, a mass spectrometry (MS) screening was performed to identify novel biomarkers and the best candidates were validated by ELISA. The urine quantification of PEDF, HPX, CD99, CANX, FCER2, HRNR, and KRT13 showed superior performance compared to PSA. Additionally, the combination of two biomarkers and patient age resulted in an AUC of 0.8196 (PSA = 0.6020) and 0.7801 (PSA = 0.5690) in detecting healthy men and high-grade PCa, respectively. In this study, we identified and validated novel urine biomarkers for the screening of PCa, showing that an upfront urine test, based on quantitative biomarkers and patient age, is a feasible method to reduce the number of unnecessary prostate biopsies and detect both healthy men and clinically significant PCa.

Immunohistochemical staining patterns of p53 predict the mutational status of TP53 in oral epithelial dysplasia

Next-generation sequencing of oral squamous cell carcinoma (OSCC) has revealed TP53 as the most frequently mutated gene in OSCC mutually exclusive with human papillomavirus infection. Oral epithelial dysplasia (OED) is defined as a precancerous lesion of OSCC by the current World Health Organization (WHO) classification; therefore, it is assumed that TP53 mutations occur in early precancerous conditions such as OED. Here, we conducted an integrated analysis of TP53, including whole coding sequencing of TP53, FISH analysis of the 17p13.1 locus, and immunohistochemical analysis for p53 (p53-IHC), in 40 OED cases. We detected 20 mutations in 16 (40%) OED cases, and four cases, each harbored two mutations. FISH analysis revealed six of 24 cases (25%) had a deletion on 17p13.1, and four cases had concurrent TP53 mutations and 17p13.1 deletion (2-hit). Also, the increased frequency of TP53 mutations in higher degrees of OED implies acquisition of the mutation is a major event toward OSCC. p53-IHC revealed that overall cases could be categorized into four patterns that correlate well with the mutational status of TP53. Especially, two patterns, broad p53 expression type (pattern HI) and p53 null type (pattern LS), strongly correlated with a missense mutation and nonsense mutation, respectively. Furthermore, seven of the 40 cases progressed to SCC, and six of these seven cases presented pattern HI or LS. Therefore, patterns HI and LS have a high risk for malignant transformation if excisional treatment is not performed irrespective of the dysplasia grade. Although the current WHO classification mainly focuses on morphological criteria for the diagnosis of OED, interobserver discrepancy appears in some instances of the OED diagnosis. Our immunohistochemical analysis supports a more accurate pathological diagnosis for OED in cases of low dysplastic changes or of differential diagnosis with non-dysplastic lesions.

Combined loss of expression of involucrin and cytokeratin 13 is associated with poor prognosis in squamous cell carcinoma of mobile tongue

BACKGROUND

This study aimed to evaluate the prognostic significance of expression levels of involucrin (IVL), cytokeratin (CK)-10 and -13 at different intratumor sites (tumor center and invading area) of oral tongue squamous cell carcinoma (OTSCC).

METHODS

IVL, CK13 and CK10 expression levels were examined in a multicenter cohort of 146 OTSCCs using immunohistochemistry. External mRNA datasets were used for expression analysis and/or to validate survival associations.

RESULTS

External transcriptomic datasets showed downregulation of IVL and KRT13 in oral malignancies including OTSCC as compared to normal controls. The combined loss of IVL and CK13 expression at the invading core but not at the center core was significantly associated with poor differentiation and reduced 5-year overall survival. Multivariate Cox analysis confirmed the loss of CK13 and IVL expression to be an independent prognostic factor. Transcriptomic dataset corroborated immunohistochemistry results.

CONCLUSIONS

Combined expression levlels of IVL and CK13 might be useful as prognostic biomarkers in OTSCC.

Enhanced KRT13 gene expression bestows radiation resistance in squamous cell carcinoma cells

Cancer metastasis and recurrence are potentially lethal. A small number of cancer cell groups called cancer stem cells (CSCs) have both stem cell capacity and cancer-forming ability and are reported to play important roles in cancer metastasis and recurrence. These CSCs are considered to be radiation-resistant (RR). Therefore, understanding the biological effects of radiation on squamous cell carcinoma (SCC) cell lines in vitro and in vivo might be worthwhile to circumvent radiation resistance. Currently, there are no reports on the establishment of RR-SCC cells in serum-free defined culture, which mimics biological mechanisms and prevents instability of using serum in the culture medium. We isolated radiation-resistant strains, designated A431-LDR and A431-HDR, from A431 cells derived from vulval SCC and irradiated them with a total dose of 60 Gy at a low-dose rate (2.2 Gy/d) (RM1000) and a high-dose rate (5 Gy/5.75min) in serum-free defined culture. These cells exhibited high sphere-forming and migration ability in vitro and high tumor-forming ability in nude mice xenografts. Overexpression of KRT13 in A431-RR cells might play a role in its radiation-resistant characteristics. These cells might be useful not only to study cancer stem cells but also to study the circumvention of radiation resistance by novel cancer treatment modalities.

Differentiated vulvar intraepithelial neoplasia (dVIN): the most helpful histological features and the utility of cytokeratins 13 and 17

Differentiated vulvar intraepithelial neoplasia (dVIN) is the precursor lesion of HPV-negative vulvar squamous cell carcinoma (VSCC). The histopathological diagnosis of dVIN can be challenging, as it often resembles vulvar non-neoplastic epithelial disorders (NNED), especially lichen sclerosus (LS). We aimed to establish the most specific and reproducible histological features of dVIN and assessed cytokeratin 13 (CK13) and cytokeratin 17 (CK17) immunohistochemistry as a diagnostic aid. Consecutive cases of dVIN (n = 180) and LS (n = 105) from the period 2010 to 2013 were reviewed using a checklist of histological features. Each feature was recorded as ‘present’ or ‘absent’ and statistical comparison (dVIN vs LS) was made. Interobserver agreement between two pairs of pathologists was assessed for a subset of cases of dVIN (n = 31) and LS and other NNED (n = 23). Immunohistochemistry with CK13, CK17, MIB1 and p53 was performed on dVIN, LS, and other NNED cases. Macronucleoli, features of disturbed maturation and angulated nuclei were significantly more common in dVIN than LS (p < 0.001). We found ‘substantial agreement’ for the diagnosis of dVIN (κ = 0.71). Macronucleoli and deep keratinisation had the highest agreement. In dVIN, the mean percentage of cells staining with CK13 was 15 and with CK17, this was 74. For LS, the mean percentage of cells staining with CK13 was 31, and with CK17, this was 41. By plotting receiver operating characteristic curves (ROC), an area under the curve (AUC) of 0.52 was obtained for CK13, and an AUC of 0.87 was obtained for CK17. The most helpful histological features for diagnosing dVIN were macronucleoli, features of disturbed maturation, and angulated nuclei. Increased CK17 expression may have promise for supporting dVIN diagnosis.

Keratin 13 gene is epigenetically suppressed during transforming growth factor-β1-induced epithelial-mesenchymal transition in a human keratinocyte cell line

Epithelial-mesenchymal transition (EMT) is a biological event in which epithelial cells lose their polarity and cell-cell adhesions and concomitantly acquire mesenchymal traits, and is thought to play an important role in pathological processes such as wound healing and cancer progression. In this study, we evaluated transforming growth factor (TGF)-β1-treated human keratinocyte HaCaT cells as an in vitro model of EMT. HaCaT cells were changed into an elongated fibroblast-like morphology, which is indicative of EMT in response to TGF-β1. Phalloidin staining demonstrated the formation of actin stress fibers in TGF-β1-treated cells. Quantitative RT-PCR analysis revealed that TGF-β1 increased the mRNA levels of EMT transcription factors (SNAI2, TWIST1, and ZEB1) and mesenchymal markers (CDH2, VIM, and FN1), while it decreased the transcripts of epithelial phenotypic genes (CLDN1, OCLN, KRT5, KRT15, KRT13, and TGM1). Furthermore, we found that KRT13 was drastically suppressed through the reduction of RNA polymerase II occupancy of its promoter, which was accompanied by a decrease in active histone marks (H3K4me3 and H3K27ac) and an increase in a repressive mark (H3K27me3) during EMT. These findings indicate that the TGF-β1-induced EMT program regulates a subset of epithelial and mesenchymal marker genes, and that KRT13 is transcriptionally suppressed through the modulation of the chromatin state at the KRT13 promoter in HaCaT cells.

Differential diagnosis of well-differentiated squamous cell carcinoma from non-neoplastic oral mucosal lesions: New cytopathologic evaluation method dependent on keratinization-related parameters but not nuclear atypism

BACKGROUND

The cytology of oral squamous cell carcinoma (SCC) is challenging because oral SCC cells tend to be well differentiated and lack nuclear atypia, often resulting in a false negative diagnosis. The purpose of this study was to establish practical cytological parameters specific to oral SCCs.

METHODS

We reviewed 123 cases of malignancy and 53 of non-neoplastic lesions of the oral mucosa, which had been diagnosed using both cytology and histopathology specimens. From those, we selected 12 SCC and 4 CIS cases that had initially been categorized as NILM to ASC-H with the Bethesda system, as well as 4 non-neoplastic samples categorized as LSIL or ASC-H as controls, and compared their characteristic findings. After careful examinations, we highlighted five cytological parameters, as described in Results. Those 20 cytology samples were then reevaluated by 4 independent examiners using the Bethesda system as well as the 5 parameters.

RESULTS

Five cytological features, (i) concentric arrangement of orangeophilic cells (indicating keratin pearls), (ii) large number of orangeophilic cells, (iii) bizarre-shaped orangeophilic cells without nuclear atypia, (iv) keratoglobules, and (v) uneven filamentous cytoplasm, were found to be significant parameters. All malignant cases contained at least one of those parameters, while none were observed in the four non-neoplastic cases with nuclear atypia. In reevaluations, the Bethesda system did not help the screeners distinguish oral SCCs from non-neoplastic lesions, while use of the five parameters enabled them to make a diagnosis of SCC.

CONCLUSION

Recognition of the present five parameters is useful for oral SCC cytology. Diagn. Cytopathol. 2017;45:406-417. © 2017 Wiley Periodicals, Inc.

Heterogeneous and abnormal localization of desmosomal proteins in oral intraepithelial neoplasms

To study the relationship between the biological and morphological characteristics of oral intraepithelial neoplasms (OINs), we examined the localization of desmosome-related proteins. Twenty-seven cases of OIN3 were tentatively classified as basaloid (14 cases) or differentiated (13 cases), and the latter were further subdivided into verrucous (five cases) and acanthotic (eight cases) subtypes. All samples were stained using antibodies against desmoglein 1 (DSG1), desmocollin 3 (DSC3), junction plakoglobin (JUP) and serine peptidase inhibitor Kazal type 5 (SPINK5) domain. All variants of OIN3 showed significantly high rates of positivity for DSG1 in the basal layer (basaloid 57%; differentiated 85%), DSC3 in the surface layer (basaloid 93%; differentiated 77%) and JUP in the basal and parabasal layers (basaloid 93%; differentiated 62%). Interestingly, even the basaloid type showed areas of alternating DSG1 positivity and negativity, reflecting keratinocyte maturation. Therefore, most cases of OIN appear to have the characteristics of well differentiated squamous epithelium.

Differential immunohistochemical expression profiles of perlecan-binding growth factors in epithelial dysplasia, carcinoma in situ, and squamous cell carcinoma of the oral mucosa

The intercellular deposit of perlecan, a basement-membrane type heparan sulfate proteoglycan, is considered to function as a growth factor reservoir and is enhanced in oral epithelial dysplasia and carcinoma in situ (CIS). However, it remains unknown which types of growth factors function in these perlecan-enriched epithelial conditions. The aim of this study was to determine immunohistochemically which growth factors were associated with perlecan in normal oral epithelia and in different epithelial lesions from dysplasia and CIS to squamous cell carcinoma (SCC). Eighty-one surgical tissue specimens of oral SCC containing different precancerous stages, along with ten of normal mucosa, were examined by immunohistochemistry for growth factors. In normal epithelia, perlecan and growth factors were not definitely expressed. In epithelial dysplasia, VEGF, SHH, KGF, Flt-1, and Flk-1were localized in the lower half of rete ridges (in concordance with perlecan, 33-100%), in which Ki-67 positive cells were densely packed. In CIS, perlecan and those growth factors/receptors were more strongly expressed in the cell proliferating zone (63-100%). In SCC, perlecan and KGF disappeared from carcinoma cells but emerged in the stromal space (65-100%), while VEGF, SHH, and VEGF receptors remained positive in SCC cells (0%). Immunofluorescence showed that the four growth factors were shown to be produced by three oral SCC cell lines and that their signals were partially overlapped with perlecan signals. The results indicate that perlecan and its binding growth factors are differentially expressed and function in specific manners before (dysplasia/CIS) and after (SCC) invasion of dysplasia/carcinoma cells.

Loss of cytokeratin 10 indicates malignant transformation in actinic cheilitis

OBJECTIVES

The aim of this study was to investigate the relationship the expression of cytokeratins (CK10 and CK13) and the cell proliferation index determined by Ki-67 of lip squamous cell carcinoma and actinic cheilitis with different degrees of dysplasia.

MATERIALS AND METHODS

Forty-five paraffin-embedded actinic cheilitis with and without dysplasia and 20 lip squamous cell carcinoma were analyzed by immunohistochemistry using anti-human anti-CK10, anti-CK13, and anti-Ki-67 antibodies.

RESULTS

The majority of actinic cheilitis showed immunopositivity for CK10 and CK13 with decrease or loss of expression in dysplastic areas. In lip squamous cell carcinoma of the lip, heterogeneous expression of CK13 and immunonegativity for CK10 were observed. There was a statistically significant difference between CK10 expression in lip squamous cell carcinoma and in actinic cheilitis with or without dysplasia (p < 0.001). The cell proliferation index was higher in actinic cheilitis with dysplasia and lip squamous cell carcinoma than in actinic cheilitis without epithelial dysplasia. A significant correlation was found between the intensity of the epithelial dysplasia and the cell proliferation index (p < 0.001).

CONCLUSION

These results provide evidence that there is a downregulation of CK10 expression in dysplastic areas of patients with actinic cheilitis and in those with lip squamous cell carcinoma (LSCC) and that the index of cell proliferation, determined by Ki-67, is directly correlated with the intensity of the epithelial dysplasia.

CLINICAL RELEVANCE

Altogether, these results suggest that CK10 expression and the epithelial cell proliferation index can help to identify malignant transformation in the lip region.

Differential Expression of Cytokeratin 13 in Non-Neoplastic, Dysplastic and Neoplastic Oral Mucosa in a High Risk Pakistani Population

BACKGROUND

Gradual loss of cytokeratin 13 (CK13) may be linked with the severity of dysplastic changes and transformation to malignancy. In this study we assessed the differential expression of CK13 in normal, hyperplastic, dysplastic and cancerous oral mucosa.

MATERIALS AND METHODS

A total of 93 oral biopsies were collected during the 2011-2014 period. The biopsies were characterized as normal (19), hyperplastic (21), severely dysplastic/carcinoma in situ (16) and invasive oral squamous cell carcinoma (OSCC) (37) after morphological assessment. Formalin fixed paraffin embedded sections were stained with a monoclonal antibody against CK13 using the Envision technique. Immunohistochemically stained slides were then analyzed for CK13 expression.

RESULTS

CK13 was consistently and diffusely expressed in all normal and hyperplastic tissue biopsies from oral mucosa. Severely dysplastic/carcinoma in situ biopsies showed complete loss in 50% of cases, while in the remaining 50% expression was very focal and weak. OSCC cases showed complete or near complete loss of CK13 in all cases. Few cases showed weak expression in keratin pearls only.

CONCLUSIONS

This study validates the utility of CK13 IHC as a useful immunohistochemical marker in routine diagnostic practice to make distinction between non-neoplastic from dysplastic and neoplastic (malignant) oral lesions.

Overexpression of lipocalins and pro-inflammatory chemokines and altered methylation of PTGS2 and APC2 in oral squamous cell carcinomas induced in rats by 4-nitroquinoline-1-oxide

Oral squamous cell carcinomas (OSCC) induced in F344 rats by 4-nitroquinoline-1-oxide (4-NQO) demonstrate considerable phenotypic similarity to human oral cancers. Gene expression studies (microarray and PCR) were coupled with methylation analysis of selected genes to identify molecular markers of carcinogenesis in this model and potential biochemical and molecular targets for oral cancer chemoprevention. Microarray analysis of 11 pairs of OSCC and site-matched phenotypically normal oral tissues from 4-NQO-treated rats identified more than 3500 differentially expressed genes; 1735 genes were up-regulated in rat OSCC versus non-malignant tissues, while 1803 genes were down-regulated. In addition to several genes involved in normal digestion, genes demonstrating the largest fold increases in expression in 4-NQO-induced OSCC include three lipocalins (VEGP1, VEGP2, LCN2) and three chemokines (CCL, CXCL2, CXCL3); both classes are potentially druggable targets for oral cancer chemoprevention and/or therapy. Down-regulated genes in 4-NQO-induced OSCC include numerous keratins and keratin-associated proteins, suggesting that alterations in keratin expression profiles may provide a useful biomarker of oral cancer in F344 rats treated with 4-NQO. Confirming and extending our previous results, PTGS2 (cyclooxygenase-2) and several cyclooxygenase-related genes were significantly up-regulated in 4-NQO-induced oral cancers; up-regulation of PTGS2 was associated with promoter hypomethylation. Rat OSCC also demonstrated increased methylation of the first exon of APC2; the increased methylation was correlated with down-regulation of this tumor suppressor gene. Overexpression of pro-inflammatory chemokines, hypomethylation of PTGS2, and hypermethylation of APC2 may be causally linked to the etiology of oral cancer in this model.

Keratins in health and disease

The cytoprotective keratins (K) compose the intermediate filaments of epithelial cells and their inherited and spontaneous mutations give rise to keratinopathies. For example, mutations in K1/K5/K10/K14 cause epidermal skin diseases whereas simple epithelial K8/K18/K19 variants predispose to development of several liver disorders. Due to their abundance, tissue- and context-specific expression, keratins constitute excellent diagnostic markers of both neoplastic and non-neoplastic diseases. During injury and in disease, keratin expression levels, cellular localization or posttranslational modifications are altered. Accumulating evidence suggests that these changes modulate multiple processes including cell migration, tumor growth/metastasis and development of infections. Therefore, our understanding of keratins is shifting from diagnostic markers to active disease modifiers.

Epigenetic alterations of the keratin 13 gene in oral squamous cell carcinoma

Background

Epigenetic modifications play important roles in the regulation of gene expression determining cellular phenotype as well as various pathologies such as cancer. Although the loss of keratin 13 (KRT13) is reportedly linked to malignant transformation of oral epithelial cells, the molecular mechanisms through which KRT13 is repressed in oral squamous cell carcinoma (OSCC) remain unclear. The aim of this study is to identify the epigenetic alterations of the KRT13 gene in OSCCs.

Methods

We investigated KRT13 expression levels and chromatin modifications of the KRT13 promoter in the three OSCC cell lines (HSC4, HSC3, and SAS). The expression levels of KRT13 protein and mRNA were analyzed by western blotting and quantitative reverse-transcription polymerase chain reaction, respectively, and the localization of KRT13 protein was detected by immunofluorescence. DNA methylation and histone modifications in the KRT13 promoter were determined by bisulfite sequencing and chromatin immunoprecipitation (ChIP), respectively. For the pharmacological depletion of Polycomb repressive complex 2 (PRC2), cells were treated with 3-deazaneplanocin A (DZNep).

Results

KRT13 expression was transcriptionally silenced in the HSC3 and SAS cells and post-transcriptionally repressed in the HSC4 cells, while the KRT13 promoter was hypermethylated in all of the three OSCC cell lines. ChIP analysis revealed that PRC2-mediated trimethylation of Lys 27 on histone H3 (H3K27me3) was increased in the KRT13 promoter in the HSC3 and SAS cells. Finally, we demonstrated that the treatment of SAS cells with DZNep reactivated the transcription of KRT13 gene.

Conclusions

Our data provide mechanistic insights into the epigenetic silencing of KRT13 genes in OSCC cells and might be useful for the development of diagnostic markers and novel therapeutic approaches against OSCCs.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-988) contains supplementary material, which is available to authorized users.

Keratin pearl degradation in oral squamous cell carcinoma: reciprocal roles of neutrophils and macrophages

BACKGROUND

We have reported that neutrophilic infiltration was associated with round-shaped dyskeratosis foci, a kind of keratin pearl, of oral carcinoma in situ and that those inflammatory cells are recruited from intra-epithelially entrapped blood vessels. Based on these lines of evidence, we have formulated a hypothesis that keratin pearls are terminally degraded by neutrophils. To confirm this hypothesis, we investigated immunohistochemically stepwise degradation of keratin pearls in oral squamous cell carcinoma (SCC) to clarify any other type scavenger cells in addition to neutrophils are involved in this particular degradation process.

METHODS

Neutrophils (neutrophil elastase) and macrophage subpopulations (CD68, CD163 and CD204) were immunohistochemically localized in 30 cases of oral SCC with typical round-shaped keratin pearls. SCC cells were revealed by immunohistochemistry for keratin (K) 17, and blood vessels were demonstrated by CD31.

RESULTS

Keratin pearl degradation process was divided into four steps: (i) intact stage: no macrophage infiltration but minimal neutrophils were found in keratin pearls; (ii) neutrophil recruit stage: no macrophage infiltration but focal neutrophilic infiltration within the pearls; (iii) neutrophil predominant stage: dense neutrophil infiltration with minimal macrophages and segregated keratinized cancer cells strongly positive for K17; and (iv) macrophage predominant stage: dense infiltration of CD68-, CD163 (mononuclear)- and CD204 (multinucleated)-positive macrophages engulfing detached keratinized SCC cells.

CONCLUSION

Keratin pearl degradation in oral SCC is strictly regulated by two types of scavenger cells: neutrophils, which perform initial tasks, and macrophages, which reciprocally take over from neutrophils the role to finalize the degradation processes.

Evaluation of superficial oral squamous cell malignancy based on morphometry and immunoexpression of cytokeratin 13 and cytokeratin 17

OBJECTIVE

Evaluation of combined morphometry and immunoexpression of cytokeratin 13 (CK13) and cytokeratin 17 (CK17) for cytological identification of superficial oral squamous cells.

STUDY DESIGN

Smears from 11 tongue squamous cell carcinoma patients were processed by liquid-based cytology, stained via the Papanicolaou method and divided into multiple specimens by cell transfer. Morphometric indices, including nuclear area, nuclear perimeter, nuclear circular rate, largest-to-smallest dimension ratio of the nucleus and nucleocytoplasmic ratio, were measured using a computerized analysis system. CK13 and CK17 were detected by immunostaining. Morphometric values were compared between cell populations with distinct staining and immunoexpression patterns.

RESULTS

Most orange G-stained superficial cells were negative for CK13 (99.4%) and CK17 (98.6%). For light green-stained superficial cells, loss of CK13 was associated with greater cellular atypia in the nuclear area, nuclear perimeter and nucleocytoplasmic ratio (p < 0.01), while expression of CK17 was related to higher-grade cellular atypia in the same parameters (p < 0.01) as well as the nuclear circular rate (p < 0.05).

CONCLUSION

Immunoexpression of CK13 and CK17 in light green-stained superficial cells was associated with more severe morphological atypia. Combined morphometry and immunoexpression of CK13 and CK17 might be useful for cytological diagnosis of this cell population.

Distinct expression patterns and roles of aldehyde dehydrogenases in normal oral mucosa keratinocytes: differential inhibitory effects of a pharmacological inhibitor and RNAi-mediated knockdown on cellular phenotype and epithelial morphology

Aldehyde dehydrogenases (ALDHs), enzymes responsible for detoxification and retinoic acid biosynthesis, are considered a potent functional stem cell marker of normal and malignant cells in many tissues. To date, however, there are no available data on ALDH distributions and functions in oral mucosa. This study aims to clarify the levels and types of ALDH expression using immunohistochemistry with accompanying mRNA expression as well as an ALDEFLUOR assay, and to assess phenotypic and histological changes after manipulation of the ALDH activity of oral keratinocytes to increase the potency of a tissue-engineered oral mucosa by a specific ALDH inhibitor, diethylaminobenzaldehyde (DEAB), together with small interfering RNA of ALDH1A3 and ALDH3A1. Results showed the mRNA and cytoplasmic protein expression of ALDH1A3 and ALDH3A1 to be mostly localized in the upper suprabasal layer although no ALDH1A1 immunoreaction was detected throughout the epithelium. Oral keratinocytes with high ALDH activity exhibited a profile of differentiating cells. By pharmacological inhibition, the phenotypic analysis revealed the proliferating cell-population shifting to a more quiescent state compared with untreated cells. Furthermore, a well-structured epithelial layer showing a normal differentiation pattern and a decrease in Ki-67 immunopositive basal cells was developed by DEAB incubation, suggesting a slower turnover rate efficient to maintain undifferentiated cells. Histological findings of a regenerated oral epithelium by ALDH1A3 siRNA were similar to those when treated with DEAB while ALDH3A1 siRNA eradicated the epithelial regenerative capacity. These observations suggest the effects of phenotypic and morphological alterations by DEAB on oral keratinocytes are mainly consequent to the inhibition of ALDH1A3 activity.

C-reactive protein: vascular risk marker in elderly patients with mental illness

BACKGROUND

There is increasing evidence that vascular disease contributes to cognitive impairment and dementia. Clarification of the role of vascular risk factors in dementia is important because most are modifiable, in contrast to other risk factors such as age and genetics.

METHODS

In 428 patients with mental illness we have investigated the relation of vascular disease to diagnoses, and a biochemical parameter, C-reactive protein (CRP), which is associated with inflammation and vascular disease.

RESULTS

Patients with vascular disease showed higher CRP levels than patients without vascular disease. Furthermore, patients with Alzheimer's disease showed lower CRP levels than patients with vascular dementia, mild cognitive impairment or depression. There is no obvious reason for this finding, since it could not be attributed to drug treatment.

CONCLUSION

The findings indicate that the control of conventional vascular risk factors and therapy could be guided by the level of CRP.